1. Field of the Invention
The present invention relates to a data processing apparatus, an information processing method, and a program.
2. Description of the Related Art
An information processing system is known which is capable of going into a power saving state to reduce power consumption in a waiting state. Such an information processing system may include, for example, a controller (main controller) including a main CPU and a network controller including a sub CPU. In the power saving state in such a system, supplying electric power to modules in the main controller is stopped, while maintaining supplying normal electric power to modules in the network controller which does not consume much electric power, during a waiting operation. In such a system, when a particular type of packet is received via a network, the network controller may respond to the received packet while maintaining the state in which no electric power is supplied to the main controller thereby achieving a reduction in power consumption. This technique is known as proxy response. A further detailed description of the proxy response technique may be found, for example, in Japanese Patent Laid-Open No. 2008-301077. In the power saving state according to such a conventional proxy response technique, each time the network controller receives a packet, the network controller checks a data pattern of the received packet to determine whether the packet is an ARP (Address Resolution Packet) request packet addressed to the network controller. Furthermore, in the power saving state, whenever the network controller receives a packet, the network controller checks a data pattern of the received packet to determine whether the received packet is a packet (a wakeup packet) which is to be handled by the main controller and thus whether the main controller is to be returned from the power saving mode. In a case where the network controller determines, from the data pattern, that the received packet is an ARP request packet, the network controller transmits, as an ARP response packet, transmission data stored in a transmission data register over a LAN (i.e., the network controller performs proxy response). On the other hand, in a case where it is determined from a data pattern of the received packet that the received packet is a wakeup packet, the network controller outputs a wakeup signal to the main controller to make the main controller return from the power saving mode.
In the conventional technique, a device including a network controller has fixed data indicating various kinds of data patterns used in a pattern matching process to determine a process to be performed, such as a proxy response process, a wakeup process, or the like. On the other hand, a recent trend is to remotely manage many kinds of devices by an application or an OS (Operating System) using a management protocol such as an SNMP (Simple Network Management Protocol) protocol. Thus, packets received by devices are different in type depending on user's devices or operation environments, and therefore it is difficult to predict the type of packets received by the respective user's devices.
Therefore, even when data patterns are registered in advance in devices thereby to determine an operation to be performed, such as a proxy response operation, a wakeup operation, etc., there is a possibility that a device is unpredictably returned from the power saving state without performing proxy response depending on the manner in which the device is operated. Depending on a situation, unexpected matching with a data pattern may occur, which may cause the power saving state to be cancelled unnecessarily. To avoid such an unnecessary operation, all possible data patterns may be registered. However, in the power saving state (a power saving mode in which devices operate with relatively low electric power), a network controller and associated units operate with limited resources to minimize power consumption, and thus it is difficult to register all possible data patterns.